The Metro was getting on a bit 10 years ago when I was flying them and probably wouldn't be worth a significant investment in upgrading to modern standards. We had a few variations in the avionics and instrumentation ranging from basic trainer panel with mono chrome radar up to flight director and colour radar.
Post #2 has described things pretty accurately, a few big bills can easily tip a GA operator on thin margins into the red. A mate wrote up a snag which resulted in a $20 000 bill, luckily he was with the RFDS !